Mode I and mode II stress intensity factors (SIFs) through the thickness of edge crack in semi circular bend (SCB) and center cracked circular disc (CCCD) specimens have been analyzed using three dimensional finite element analysis. The effect of the CCCD and SCB specimen thickness on the through-thickness variations of SIFs has been studied. For all mode of mixity, the peak value of mode I SIF is found at mid plane of SCB specimen and for thin CCCD specimen, while, this location is shifted to be near the free surface plane in thick CCCD specimen. The variation of mode II SIF in CCCD and SCB specimens have a similar trend.

The novel equivalent material concept, proposed originally by the author, was utilized together with the mean stress and the point stress failure concepts to predict the load-carrying capacity of O-notched ductile steel plates under pure tension. Unlike for V and U-notches, it was found that the point stress criterion combined with the equivalent material concept could estimate successfully the limited available experimental results reported in literature regarding four O-notched plates made of very ductile steel. By using the model, one may predict well the onset of tensile crack initiation in O-notched ductile components without requiring performing experiments or elastic-plastic analysis.

Semi-submersible drilling platforms are huge bulk structures for extracting the oil products from great depth of seas. For such bulk structures, the Morrison’s equations are no longer valid for determining the loads applied to the semi-submersible drilling platforms. The diffraction theory should be used for evaluating the hydrodynamic interactions between the platform and the sea waves. In this theory, the Laplace equation is solved by considering the boundary conditions of the diffraction theory. In this paper, after a brief description of the diffraction theory, the hydrodynamic interactions between the Iran’s Amirkabir semi-submersible drilling platform and the regular linear waves of Caspian Sea is investigated numerically using boundary element method in the ANSYS/AQWA software. The induced waves exciting forces and moments with different wave heading angles are estimated for six degrees of freedom relative to the waves frequencies using the diffraction theory. The performed hydrodynamic analysis is also validated with the previous works performed for Spar platforms.

In this paper, the stress intensity factors (SIFs) for an interfacial notch in a bi-material joint have been calculated using the experimental method of photoelasticity. A bi-material Brazilian disc specimen with a central interface notch was employed to determine the SIFs for different mode mixities. In this approach, SIFs were calculated experimentally for an Al/Polycarbonate bi-material Brazilian disc specimen and two different loading angles (i.e. modes I and II dominated loading conditions). The results of experimental approach were then compared with the numerical values of finite element method. Experimental results were in good consistency with the numerical values.